| 5 | ÷ | 2 | × | x | + | 5 | ÷ | 7 | × | ( | 50 | − | x | ) | = | 30 |
| 方程左边 = | 5 2 | x | + | 5 7 | ( | 50 | − | x | ) |
5 2 | x | + | 5 7 | ( | 50 | − | x | ) | = | 30 |
| 方程左边 = | 5 2 | x | + | 5 7 | × | 50 | − | 5 7 | x |
| = | 5 2 | x | + | 250 7 | − | 5 7 | x |
| = | 25 14 | x | + | 250 7 |
25 14 | x | + | 250 7 | = | 30 |
25 14 | x | = | 30 | − | 250 7 |
25 14 | x | = | - | 40 7 |
| x | = | - | 40 7 | ÷ | 25 14 |
| = | - | 40 7 | × | 14 25 |
| = | - | 8 | × | 2 5 |
| x | = | - | 16 5 |
| x | = | - 3.2 |